DO NOW:

1. DO NOW: • Describe the early earth. • What was the first type of life like? • How did the experiments of Spanallzani, Pasteur, and Redi influence the way scientists viewed life?

2. Evolution: How species have changed over time

3. First a Perspective of Time

4. Those who influenced Darwin

5. GEOLOGYHutton and Lyell (geologists • James Hutton (1785) • hypothesized earth to be very old when he examined geologic features such as rock layers and erosion • Charles Lyell (1833) • Hypothesized that complex geologic processes like erosion, volcanoes, etc. shaped the earth as we currently see it. • CONCLUSIONS: • EARTH IS VERY VERY OLD! • Today’s best guess???  4.6 Billion Years

6. 1809:Lamarck’s Theory • Use and Disuse: • Body parts that are used more grow stronger and bigger. • Body parts not used will deteriorate. • Inheritance of Acquired Characteristics: • Physical changes that occur in an organism are inherited by its offspring.

8. Thomas Malthus (1798) • Observed human population growth will eventually hit a limit due to living space and available food. Darwin would later apply this to all organisms where these limits result in competition. • While Lamarck's reasoning behind why change happened was flawed, Lamarck and Malthus both greatly influenced the thinking of Mr. Charles Darwin.

9. Charles Darwin-1800’s • Was a Naturalist – mostly observed organisms in their natural habitats rather than conducting experiments. • Made most of his observations on the Galapagos Islands

11. Charles Darwin • Did much of his work in the Mid-1800’s ** Keep in mind this is BEFORE Mendel, Watson and Crick***

12. Charles Darwin • Introduced the idea of Natural Selection as a way for new species to form (speciation). • Published The origin of Species in 1859

13. The Theory of Natural Selection • Assumptions: • There are not enough resources for all to survive • genetic variation exits in all populations. Results: • Competition • Survival of the fittest • Descent with modification

14. Assumption 1: Not enough resources • What resources are we talking about? Suitable Mates Food Shelter • Are there enough for everyone?

15. Assumption 2: Genetic variation exists • Where do these differences come from? Sexual reproduction Genetic Recombination Mutations Migration • Remember it doesn’t have to be a NEW gene, just a new combination of genes

16. Result 1. Competition • Individuals will compete for the limited resources. • Goal is to survive and pass on genes • “winner” gets to pass genes on at higher rate.

17. Result 2. Survival of the Fittest • Not all variations are equal. Some are better at competing in their environment than others. These individuals are more likely to “win” and survive to pass on their genes. • Fitness: an organisms ability to survive and reproduce.

18. Result 3. Descent with Modification • Descent – To come from • Modification – With changes • More of the “fit” genes will be passed on than “unfit” • In future generations, the frequencyof fit genes increases, while the frequency of unfit genes decreases.

19. 3. Descent with Modification • New generations will resemble previous generations (descent) BUT more individuals will have the “best” variation PLUS new mutations and combinations (with modification)

20. An Example

21. Example: • What is the genetic variation? • What is the selective pressure? • Who has the advantage? • What would we predict for the next generation? • Why might the “unfit” phenotype stick around?

22. Rules of Evolution • Mutations and their phenotypes are random. Meaning? • Variation must exist in the population BEFORE selective pressure occurs • If no “fit” variation exists when pressure begins, entire population dies = Extinction

23. Rules of Evolution • Individuals can not evolve, only species • A fit trait in one environment might be eliminated as a weakness in another

24. Types of Selection • Natural Selection • What determines which variation gets passed on? • What is the outcome? • Artificial Selection (a.k.a. selective breeding) • What determines which variation gets passed on? • What is the outcome?

25. Types of Selection Directional Selection: One extreme or the other is “favored” and increases in frequency while midrange and other extreme decrease

26. Types of Selection Stabilizing Selection: Midrange is favored and increases in frequency while both extremes decrease.

27. Types of Selection Diversifying/disruptive Selection: Both extremes are favored and increase while midrange decreases.

28. At what point is a new species formed? • Evolution – change in allele frequency • Speciation – such change that new population is a different species – two organisms that can successfully reproduce and produce viable, fertile offspring

29. Examples: Cross between a Pug and a Beagle - different breeds but SAME species

30. Examples: Offspring: Puggle! Both viable (obviously) and fertile

31. Examples: Cross between a Horse and Donkey - different species

32. Examples: Offspring: Mule! Viable but infertile

33. Gene Pool Isolation • Two populations become separated so their genes are no longer mixed • Mutations appear independently in each population • Selection happens independently in each population

34. Mechanisms of Isolation • Geographic – Physical barrier separates two populations • Behavioral – mating behaviors of some are not attractive to others. • Temporal – fertility occurs at different times • Mechanical – different physical means of reproduction

35. Principle of a Common Ancestor • Descent with Modification – over generations descendents can look quite different from ancestors. • Thus, organisms that seem very different might share a common ancestor • Suggests if you go far enough back, we are all related!

36. Phylogenetic tree: Family Tree of Life

37. Phylogeny • the connections between all groups of organisms as understood by ancestor/descendant relationships. • Express relationships using a CLADOGRAM

39. Common ancestor • Humans and chimps have a common ancestor. • THAT IS NOT THE SAME AS SAYING WE WERE ONCE CHIMPS!!! • Think about it: Do you and your cousin share a common ancestor? Does that mean you are your cousin? Does that mean that either of you are that ancestor?

40. Evidence of Common ancestry • Comparative Anatomy – examining body parts • Homologous structures – similar in form, but not necessarily function; • suggests common ancestor • Results from divergent evolution

41. Evidence of Common ancestry

42. Evidence of Common ancestry • Comparative Embryology – examining developmental patterns • Similar organisms follow similar developmental patterns • We all start off the same – a single egg • BUT the series of steps that follows is most similar between closely related organisms

43. Evidence of Common Ancestry

44. Evidence of Common ancestry • Comparative Biochemistry – examining DNA and protein sequences • Remember: DNA contains info to make proteins. Proteins are responsible for our traits. • Organisms with close ancestors share a large percentage of DNA.

45. Evidence of Common ancestry

46. Evidence of a Universal Common Ancestor • All life is cellular • All life encodes its information in nucleic acids • (DNA/RNA) • All life shares the same genetic code • (AUG = Met)

47. Evidence of a Universal Common Ancestor • All Life uses ATP as its energy molecule • Suggests we are all derived from the same thing and that thing had all these traits!

48. Additional Evidence of Evolution (but not necessarily common ancestry) • Fossil Record • Vestigial organs • Biogeography • Analogous traits • Convergent evolution

49. Additional Evidence of Evolution (but not necessarily common ancestry) Fossil Record • Preserved remains of ancient life in sedimentary rock • Even of species no longer in existence (most!)

50. Fossils • Fossils are often found in the layers of sedimentary rock. • See changes in fossils over time